The purpose of ERA was to ascertain if the progression of coronary atherosclerosis can be modified by hormone replacement therapy in post-menopausal women with coronary artery disease. Subjects underwent coronary arteriography at baseline and were randomized to estrogen, estrogen plus progestin or placebo. After 3 years, coronary arteriograpy was repeated. The endpoint of the study is the change in coronary arterial narrowing from baseline to follow-up.